<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<!-- 1.准备好一个“容器” -->
<div id="test"></div>
<!-- 引入react核心库 -->
<script src="../js/17.0.1/react.development.js"></script>
<!-- 引入react-dom。用于支持react操作DOM -->
<script src="../js/17.0.1/react-dom.development.js"></script>
<!-- 引入babel，用于将jsx转为js -->
<script src="../js/17.0.1/babel.min.js"></script>
<script type="text/babel">
    //定义组件
    class Time extends React.Component {
        //初始化状态
        state = {date: new Date()};

        componentDidMount() {
            setInterval(() => {
                this.setState({
                    date: new Date()
                });
            }, 1000);
        }

        render() {
            return (
                <div>
                    <h1>Hello</h1>
                    <input type="text"/>
                    <span>现在是：{this.state.date.toTimeString()}</span>
                </div>
            );
        }
    }

    ReactDOM.render(<Time/>, document.getElementById("test"));
</script>
</body>
</html>